CVE-2023-53624: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_fq: fix integer overflow of "credit" if sch_fq is configured with "initial quantum" having values greater than INT_MAX, the first assignment of "credit" does signed integer overflow to a very negative value. In this situation, the syzkaller script provided by Cristoph triggers the CPU soft-lockup warning even with few sockets. It's not an infinite loop, but "credit" wasn't probably meant to be minus 2Gb for each new flow. Capping "initial quantum" to INT_MAX proved to fix the issue. v2: validation of "initial quantum" is done in fq_policy, instead of open coding in fq_change() _ suggested by Jakub Kicinski

Affected products

• Linux Linux Kernel: from 3.12, before 5.10.180 (fixed in 5.10.180); from 5.11, before 5.15.111 (fixed in 5.15.111); from 5.16, before 6.1.28 (fixed in 6.1.28); from 6.2, before 6.2.15 (fixed in 6.2.15); from 6.3, before 6.3.2 (fixed in 6.3.2)

Published 2025-10-07. Last modified 2026-06-17.